1. Technical Field
This invention relates to an indicator operation detecting device that detects operation of an indicator such as a finger by using a sensor of the capacitive system.
2. Description of the Related Art
In the past, a trackball was used as an indicator operation detecting device to instruct, for example, moving an object displayed on a display screen of a personal computer (hereinafter, abbreviated as PC) in the horizontal direction and the vertical direction of the display screen or rotating the object. The trackball has a structure in which a ball (spherical body) is supported by rotary encoders having rotational axes along directions perpendicular to each other. In association with rolling of this ball by a finger or a palm, a cursor or an object on the display screen is moved in the horizontal direction and the vertical direction of the display screen by the movement amount corresponding to the rotation amount detected by the two rotary encoders.
However, because the trackball moves the cursor or the object by the movement amount corresponding to the rotation of the rotary encoder in association with the rotation of the ball, it can only specify the relative movement amount by this movement operation and, as a result, operation of precisely indicating a coordinate position for the cursor or the object is difficult.
On the other hand, in recent years, there have been increasing opportunities to utilize a touch panel using a sensor for position detection (hereinafter, referred to simply as the sensor) as an indication input device. In particular, the sensor of the capacitive system is superior to the sensor of the resistive film system in the past in terms of the following features, for example: the response speed is high; the durability is high; and plural indicators such as fingers can be simultaneously detected. Therefore, it is satisfactorily used in portable electronic apparatus such as a cell-phone terminal.
The capacitive sensor includes a matrix electrode pattern configured with plural elongate first electrodes parallel to each other and plural elongate second electrodes that intersect these plural first electrodes and are parallel to each other. In this sensor, the first electrodes and the second electrodes are separated from each other by, e.g., a dielectric substrate and are capacitively coupled to each other, and the configuration is so made that a transmission signal is supplied to the first electrode and a received signal is obtained from the second electrode via the capacitive coupling for example.
In this capacitive sensor, at the part with which an indicator such as a finger contacts the matrix electrode pattern, part of the transmission signal flows through the human body and thereby the received-signal current obtained from the second electrode changes. Thus, the position indicated by the indicator such as a finger is detected by detecting this change. The position indicated by the indicator is detected as the intersection of the first electrode and the second electrode.
In this case, normally, for example, a first direction along which the first electrodes are formed along the horizontal direction of the operation by the operator and this horizontal direction is defined as the X-axis direction of the two-dimensional coordinates of the position that is indicated by the indicator and is detected by the sensor. Furthermore, a second direction along which the second electrodes are formed along the vertical direction perpendicular to the horizontal direction of the operation by the operator and this vertical direction is defined as the Y-axis direction of the two-dimensional coordinates of the sensor. The sensor detects and outputs the position indicated by the indicator as the X- and Y-coordinate values on the two-dimensional coordinates.
Furthermore, as described above, the X-axis direction and the Y-axis direction of the two-dimensional coordinates of the position indicated by the indicator in the sensor are made to correspond with the horizontal direction and the vertical direction of the operation by the operator and thus are made to correspond to the horizontal direction and the vertical direction of the display screen. That is, the coordinate space defined by the X-axis direction and the Y-axis direction of the two dimensional coordinates as the output coordinates of the sensor is made to correspond to the coordinate space defined by the horizontal direction and the vertical direction of the display screen. In the following description, the coordinate space of the output coordinates of the sensor, defined by e.g., the X-axis direction and the Y-axis direction of two dimensional coordinates, will be referred to as the output coordinate space of the sensor.
For example, Patent Document 1 (Japanese Patent Laid-Open No. 2003-91360) and Patent Document 2 (Japanese Patent Laid-Open No. 2003-296014) disclose an indicator operation detecting device using a capacitive sensor like the one described above. In this device, the shape of an operation section to which position indication operation is carried out by an indicator is set to a three-dimensional shape in pursuit of the more intuitive input. Specifically, the indicator operation detecting device disclosed in patent documents 1 and 2 has an operation surface made as a curved surface by three-dimensional molding of a predetermined area of the indicator-detectable area of the matrix electrode pattern of the sensor into a dome shape.
When the operation surface is made as a curved surface, when the operator moves his finger on the operation surface with the finger in contact with the operation surface, the operator can feel, in addition to movement sensation, sensation of displacement in the height direction of the curved shape based on the inclination direction and the inclination degree of the curved surface. Therefore, according to the indicator operation detecting device described in Patent Documents 1 and 2 and having the curved operation surface, the operator can easily understand the operation position of the finger, the movement direction of the finger, and the movement amount and thus can obtain a good feel of operability.
Furthermore, according to the above-described indicator operation detecting device described in Patent Documents 1 and 2, the contact position of an indicator such as a finger is detected by the matrix electrode pattern of the sensor based on the capacitive system. Therefore, the absolute coordinates of the position indicated by the indicator can be detected and the coordinate output of indication operation is more accurate than by the trackball.